1. Field of the Invention
The invention relates to compounds of di(aryl)methyl alkyl sulfones composed of bis(4-chlorophenyl), or 2,4'-dichlorodiphenylmethyl and alkyls with one to four carbon atoms, and to methods of controlling the harmful effects of fungi upon plants with these compounds, particularly Piricularia fungi.
2. Description of the Prior Art
Because fungus causes harmful effects such as disease which affect every crop and ornamental plant, chemical compounds are required which prevent or eradicate these diseases. The action of a chemical towards a specific disease is not a priori predictable because of very complicated biochemical reactions. For example a compound may act as a respiratory enzyme which causes respiratory malfunction in the attacking plant pest, or as a hormone to stimulate a rapid growth which causes the plant pest to rapidly die, or as a metabolite within the plant which stimulates the plant to fight off the disease or kill the pest.
Fungus of the genus Piricularia, particularly the fungus Piricularia oryzae, which affects rice causing Rice Blast Disease, is a fungus which needs to be controlled. Although certain sulfides, sulfoxides and sulfones possess biochemical activity against certain organisms, as shown in the following prior art; nothing therein suggests controlling the harmful effects the Piricularia fungus with sulfones.
Bis(4-chlorophenyl)methyl methyl sulfide is active against the mosquito species, Anopheles albimanus, as described by R. L. Metcalf et al., Bulletin of the World Health Organization, Vol. 38, pages 633-647, (1968). Phenylmercaptomethane sulfonamide is described as being active against Phytophthora infestans (U.S. Pat. No. 3,412,149). Oximidomethane sulfonamides are disclosed as being active against bacteria and weeds (U.S. Pat. No. 3,549,702). 4-Methoxyphenyl diiodomethyl sulfone is shown to inhibit the growth of Aspergillus oryzae (U.S. Pat. No. 3,615,745), and 2,4,5,4'-tetrachlorodiphenyl sulfide, sulfoxide, and sulfones are shown to be effective against Red Spider Mites (U.S. Pat. No. 3,054,719). Other sulfones, sulfides, and sulfoxides are described but their activity against fungus are not known. For example, compounds of type B--X--C(Ar) (Ar')--SO.sub.2 --R wherein B is a lower aliphatic tertiary-amino group, X is a lower alkylene group, Ar and Ar' are aryl groups and R is an alkyl group, are claimed as analgetics. 4,4'-dichlorodiphenyl sulfone is claimed as an important monomer for preparing polylarylene polyethers (Belgian Pat. No. 650,476). Certain aryl sulfoxides are described by C. Shunk et al. (U.S. Pat. No. 3,466,377) as being analgetics. Other aryl sulfones are described as both analgetics and anti-pyretics by C. Shunk et al. (U.S. Pat. No. 3,637,803 and U.S. Pat. No. 3,689,567), Jean A. Gautier et al. in U.S. Pat. No. 3,624,094 describes alpha-[(phenyl sulfinyl)methyl]-alpha phenyl derivatives of pyridinemethanols as analgetics and anti-inflammatory agents.